Spreading anger over the brutal killings of high-profile Islamic State group (IS) hostages after protracted negotiations is unlikely to hurt the terror group's cash flow. Instead, there are fears the deaths actually may serve to help fill its coffers.

“The whole world is taking about this emerging caliphate and how much power they have,” said the Potomac Institute’s Yonah Alexander. “You find people contribute, including Saudi Arabians, some other countries, they contribute to their cause.”

The United States has consistently voiced concerns about IS, also known as ISIL, using grisly videos, like the one showing captive Jordanian pilot Muath al-Kaseasbeh being burned to death, to rally supporters.

“It’s not a question of whether ISIL will change tactics,” one intelligence official said on condition of anonymity. “It’s a question of whether their propaganda will continue to resonate.”

At least with the group's target audience of extremists and would-be foreign fighters, officials believe the videos have resonated strongly. Another U.S. official told VOA the Islamic State "is a good brand to have if you're a terrorist."

As a result, analysts caution there is no reason to think the Islamic State's brutal treatment, and killing, of hostages won’t continue to pay off.

“As they started doing this I think they recognized that this had tremendous propaganda value and at a certain level you can’t put a dollar figure on that,” said Matthew Levitt, a former U.S. Treasury Department official with the Washington Institute's Stein Program on Counterterrorism and Intelligence.

Officials and analysts even doubt the high-profile killings will hurt the Islamic State’s ability to continue to raise money from ransoms, a figure that reached at least $20 million in 2014.

“Certain countries have adopted a de facto policy of allowing the payment of ransoms on a case-by-case basis,” according to Treasury Department Deputy Assistant Secretary for Terrorist Financing Jennifer Fowler. Speaking earlier this week, Fowler also said the U.S. will continue to try to change the approach of countries that allow such payments.

Just how much of an impact that is having remains unclear.

“There is some evidence it’s a little harder for them [Islamic State kidnappers] to get quite as much money,” said Levitt. “They know what countries they can get money from and what countries they probably can’t.”

Not all kidnappings involve high-profile hostages, like the Jordanian pilot or Japanese or U.S. journalists. Analysts say some kidnap victims are Iraqis and Syrians who are ransomed off for relatively smaller payments.